| S/SIS | Sales/Service Information System 
| Others |
| SSIS | Saigon South International School
| Others |
| SSIS | Scandinavian Society for Iranian Studies
| Others |
| SSIS | Schedules and Schemes Information System
| Others |
| SSIS | Sequence Stratigraphic Interpretation System
| Others |
| SSIS | Shanghai Singapore International School
| Others |
| SSIS | Smart Systems Industry Summit
| Others |
| SSIS | Social Services Information System
| Others |
| SSIS | Social Skills Improvement System
| Others |
| SSIS | Space Station Information System
| Others |
| SSIS | SQL Server Integration Services
| Others |
| SSIS | Standard Sample Introduction System
| Others |
| SSIS | State Security Investigations Service
| Others |
| SSIS | Suzhou Singapore International School
| Others |
| SSIS | Swiss School In Singapore
| Others |